PLASTIC INJECTION MOLDING WITH TPE – THERMALLY MECHANICAL
GREAT BENEFIT: TPE CAN ALWAYS BE REFORMED – ANYWHERE
Unlike in elastomer injection molding, no chemical vulcanization process is initiated in thermoplastic or plastic injection molding. It is therefore a pure thermal, mechanical injection process. This process is reversible, that is, it can be repeated as often as desired by cooling and reheating to the molten state, as long as not using the so-called thermal decomposition of the material by overheating. We produce classic hard component parts, but are specialized in the processing of thermoplastic elastomers (TPE) in plastic injection molding.
THE PROCESS IN PLASTIC INJECTION:
- In granular form, the thermoplastic materials go into the interstices of the rotating screw. This promotes the granules in the direction of the screw tip. Due to the temperature of the injection cylinder and the frictional heat, which arises when shearing the material, the granules are melted. As soon as a sufficient quantity of material has been accumulated for the component volume, the dosing process is ended and the screw no longer rotates.
- For injection, the injection unit is moved to the closing unit. The melt is injected under high pressure through the opened nozzle into the mold. A backflow preventer prevents the backflow of the melt to the hopper.
- Unlike in rubber injection molding, the tool is colder tempered than the plastic melt. The melt solidifies on reaching the freezing point.
- To compensate for the shrinkage that occurs during cooling, a reduced pressure is maintained after filling the mold. This reprinting can be done until the sprue is solidified.
- After pressing, the nozzle is closed and the next cycle begins while the cooling time is running and the workpiece is solidified, or sufficient rigidity for demolding is achieved.
- The demoulding can be done by ejector pins and the components fall down (bulk material). Alternatively, the parts can also be removed with a robot and placed on conveyor belts in controlled fashion.
PLASTIC INJECTION MOLDING WITH HOT CHANNEL
The sprue can either be granulated and returned to the melt or recycled separately. Angeless injection molding is possible with a hot runner that keeps the melt permanently above the solidification temperature. A hot runner makes sense, especially for large components and larger quantities, since the entire injection process can be better controlled and no handling of the sprue waste is required.
PLASTIC INJECTION WITH PROTECTION OF THE ENVIRONMENT
We support the use of plastic recyclate to protect the environment whenever possible and approved by the customer.
Most of our plastic injection molding machines use gaskets and other elastic TPE molded parts. Another focus is the production of thermoplastic inserts, which are encapsulated in further processing steps with EPDM or TPE (insert molding). For the so-called insert molding we have several vertical injection molding machines available.
Typical injection molded parts from two components. Instead of labor-intensive assembly of sealing rings to individual hard components, we offer hard and soft composite molded parts by direct multi-component injection molding. The direct gating of elastic materials saves labor costs and leads to higher quality products. Take a look at the multi-component injection molding process.